Stabilization of fluorophosphite-containing catalysts

ABSTRACT

Disclosed are novel catalyst systems comprising (1) a diorgano fluorophosphite ligand; (2) rhodium, wherein the ratio of gram moles fluorophosphite ligand (1) to gram atoms of rhodium is at least 1:1; and (3) a Group VIII metal, other than rhodium, or Group VIII metal-containing compound, in an amount effective to reduce the formation of HF during the use of the catalyst system. The presence of the other Group VIII metal decreases the amount of hydrogen fluoride produced during the use of the catalyst system. The hydrogen fluoride originates from very low level degradation of the ligand. Also disclosed are novel catalyst solutions of the aforesaid catalyst system and the use of the catalyst system in the hydroformylation of olefins to produce aldehydes.

FIELD OF THE INVENTION

[0001] The present invention pertains to a novel catalyst systemcomprising (1) a diorgano fluorophosphite ligand; (2) rhodium; and (3) aGroup VIII metal, other than rhodium, or Group VIII metal-containingcompound, in an amount effective to reduce the formation of HF duringthe use of the catalyst system. The presence of the other Group VIIImetal decreases the amount of hydrogen fluoride produced during the useof the catalyst system. The hydrogen fluoride originates from very lowlevel degradation of the ligand. The present invention also pertains tocatalyst solutions of the aforesaid catalyst system and the use of thecatalyst system in the hydroformylation of olefins to produce aldehydes.

BACKGROUND OF THE INVENTION

[0002] Homogenous catalyst solutions prepared from transition metals andphosphorus ligands are used widely in the chemical industry. Theadvantages of homogenous catalysts over heterogeneous catalysts usuallyinclude higher reactivity and higher selectivity. However, homogenouscatalysts often are subject to degradation and concomitant loss ofactivity over time. The problem of catalyst degradation is aggravated ifthe degradation process leads to the formation of unwanted side productsthat are found as contaminants in the product. Therefore, it is highlydesirable to develop technologies that extend the effective catalystlifetime, enhance selectivity and reduce contaminants in the product.

[0003] The hydroformylation reaction, also known as the oxo reaction, isused extensively in commercial processes for the preparation ofaldehydes by the reaction of one mole of an olefin with one mole each ofhydrogen and carbon monoxide. The most extensive use of the reaction isin the preparation of normal- and iso-butyraldehyde from propylene. Theratio of the amounts of the normal to iso aldehyde products typically isreferred to as the normal to iso (N:I) or the normal to branched (N:B)ratio. In the case of propylene, the normal- and iso-butyraldehydesobtained from propylene are in turn converted into manycommercially-valuable chemical products such as, for example, n-butanol,2-ethyl-hexanol, n-butyric acid, iso-butanol, neopentyl glycol,2,2,4-trimethyl-1,3-pentanediol, the mono-isobutyrate and di-isobutyrateesters of 2,2,4-trimethyl-1,3-propanediol. The hydroformylation ofhigher α-olefins such as 1-octene, 1-hexene, and 1-decene yield aldehydeproducts which are useful feedstocks for the preparation of detergentalcohols and plasticizer alcohols. The hydroformylation of substitutedolefins such as allyl alcohol is useful for the production of othercommercially valuable products such as 1,4-butanediol.

[0004] Catalysts used in the hydroformylation reaction typically containrhodium complexes comprising at least one phosphorus ligand. U.S. Pat.No. 3,239,566, issued Mar. 8, 1966, to Slaugh and Mullineaux, disclosesa low pressure hydroformylation process using trialkylphosphines incombination with rhodium catalysts for the preparation of aldehydes.Trialkylphosphines have seen much use in industrial hydroformylationprocesses but they typically produce a limited range of products and,furthermore, frequently are very oxygen sensitive. U.S. Pat. No.3,527,809, issued Sep. 8, 1970 to Pruett and Smith, discloses a lowpressure hydroformylation process which utilizes triarylphosphine ortriarylphosphite ligands in combination with rhodium catalysts. Theligands disclosed by Pruett and Smith, although used in many commercialapplications, have limitations due to oxidative and hydrolytic stabilityproblems. Since these early disclosures, numerous improvements have beenmade to increase the catalyst stability, catalyst activity and theproduct ratio with a heavy emphasis on yielding linear aldehyde product.A wide variety of monodentate phosphite and phosphine ligands, bidentateligands such as bisphosphites and bisphosphines as well as tridentateand polydentate ligands have been prepared and disclosed in theliterature. U.S. Pat. No. 5,840,647 discloses the use ofdiorgano-fluorophosphites, also known as fluorophosphites, as thephosphorus ligand component of hydroformylation catalysts.

[0005] It also is known that the hydroformylation catalysts suffer fromthe drawback that the phosphorus ligands can be decomposed by a varietyof mechanisms including oxidation, acid catalyzed hydrolysis, and, inthe case of certain tri-organo phosphite ligands, the rhodium-catalyzeddecomposition of the phosphite as disclosed in U.S. Pat. Nos. 5,756,855and 5,929,289. The ligand decomposition reactions are detrimental to theoverall economics of the process as they result in the loss of thevaluable ligand and also can result in the formation of liganddegradation products which may act as catalyst poisons. We have foundthat diorgano fluorophosphite compounds described in U.S. Pat. No.5,840,647 undergo low level degradation to generate hydrogen fluoridewith concomitant loss of ligand. The hydrogen fluoride contaminates theproduct aldehydes which is highly undesirable as it can lead tocorrosion and the formation of by-products.

SUMMARY OF THE INVENTION

[0006] The present invention provides a means for the stabilization ofcertain homogenous catalyst systems comprising at least one diorganofluorophosphite compound that results in the suppression of theformation of hydrogen fluoride from the catalyst systems. Thus, oneembodiment of the present invention is a novel catalyst systemcomprising (1) a diorgano fluorophosphite ligand; and (3) rhodium;wherein the ratio of gram moles fluorophosphite ligand to gram atoms ofrhodium is at least 1:1; and (3) a Group VIII metal, other than rhodium,or Group VIII metal-containing compound, in an amount effective toreduce the formation of HF during the use of the catalyst system, i.e.,during the use of the catalyst to catalyze organic processes. The novelcatalyst systems may be used in a wide variety of transitionmetal-catalyzed processes such as, for example, hydro-formylation,hydrogenation, isomerization, hydrocyanation, hydrosilation,carbonylations, oxidations, acetoxylations, epoxidations,hydroamination, dihydroxylation, cyclopropanation, telomerizatons,carbon hydrogen bond activation, olefin metathesis, olefindimerizations, oligomerizations, olefin polymerizations, olefin-carbonmonoxide copolymerizations, butadiene dimerization and oligomerization,butadiene polymerization, and other carbon-carbon bond forming reactionssuch as the Heck reaction and arene coupling reactions. The catalystsystems provided by the present invention are especially useful for thehydroformylation of olefins to produce aldehydes.

[0007] A second embodiment of our invention concerns a novel catalystsolution comprising (1) one or more diorgano fluorophosphite ligands,(2) rhodium, (3) a Group VIII metal, other than rhodium, or Group VIIImetal-containing compound, in an amount effective to reduce theformation of HF, and (4) a hydroformylation solvent. This embodimentcomprises a solution of the active catalyst in which a carbonylationprocess such as the hydroformylation of an ethylenically-unsaturatedcompound may be carried out.

[0008] A third embodiment of the present invention pertains to ahydroformylation process utilizing the above-described catalyst systemsand solutions. The process of the present invention therefore includes aprocess for preparing an aldehyde which comprises contacting an olefin,hydrogen and carbon monoxide with a solution of a catalyst systemcomprising and (1) a diorgano fluorophosphite ligand, (2) rhodium and(3) a Group VIII metal, other than rhodium, or Group VIIImetal-containing compound, in an amount effective to reduce theformation of HF, wherein the ratio of gram moles fluorophosphite ligandto gram atoms of rhodium is at least 1:1.

DETAILED DESCRIPTION OF THE INVENTION

[0009] The diorgano or dihydrocarbyl fluorophosphite component of thecatalyst of the present invention is a trivalent phosphorus compound inwhich the phosphorus atom is bonded to two oxygen atoms and one fluorineatom. The oxygen atoms are further attached to organic groups which bearomatic or alkyl groups. The organic groups may be independent groupsor may be joined together in cyclic or polymeric structures. Thefluorophosphite compounds or ligands are represented by formula (I):

[0010] wherein R¹ and R² represent the same or different hydrocarbylgroups or R¹ and R² may in combination represent joined groupsconstituting a hydrocarbylene group which, with the phosphite residue,forms a cyclic ligand compound. The hydrocarbyl and joined hydrocarbylgroups represented by R¹ and R² may be selected, for example, from thesame or different unsubstituted and substituted alkyl, cycloalkyl andaryl groups containing a total of up to about 40 carbon atoms. The totalcarbon content of substituents R¹ and R² preferably is in the range ofabout 12 to 35 carbon atoms. Examples of the alkyl groups which R¹and/or R² separately or individually can represent include ethyl, butyl,pentyl, hexyl, 2-ethylhexyl, octyl, decyl, dodecyl, octadecyl andvarious isomers thereof. The alkyl groups may be substituted, forexample, with up to two substituents such as alkoxy, cycloalkoxy,formyl, alkanoyl, cycloalkyl, aryl, aryloxy, aroyl, carboxyl,carboxylate salts, alkoxycarbonyl, alkanoyloxy, cyano, sulfonic acid,sulfonate salts and the like. Cyclopentyl, cyclohexyl and cycloheptylare examples of the cycloalkyl groups R¹ and/or R² individually canrepresent. The cycloalkyl groups may be substituted with alkyl or any ofthe substituents described with respect to the possible substitutedalkyl groups. The alkyl and cycloalkyl groups which R¹ and/or R²individually can represent preferably are alkyl of up to about 8 carbonatoms, benzyl, cyclopentyl, cyclohexyl or cycloheptyl.

[0011] Examples of the aryl groups which R¹ and/or R² individually canrepresent include carbocyclic aryl such as phenyl, naphthyl, anthracenyland substituted derivatives thereof. Examples of the carbocyclic arylgroups which R¹ and/or R² individually can represent are the radicalshaving the formulas

[0012] wherein R³ and R⁴ may represent one or more substituentsindependently selected from alkyl, alkoxy, halogen, cycloalkoxy, formyl,alkanoyl, cycloalkyl, aryl, aryloxy, aroyl, carboxyl, carboxylate salts,alkoxycarbonyl, alkanoyloxy, cyano, sulfonic acid, sulfonate salts andthe like. The alkyl moiety of the aforesaid alkyl, alkoxy, alkanoyl,alkoxycarbonyl and alkanoyloxy groups typically contain up to about 8carbon atoms. Although it is possible for m to represent 0 to 5 and forn to represent 0 to 7, the value of each of m and n usually will notexceed 2. R³ and R⁴ preferably represent halogens and/or lower alkylgroups, i.e., straight-chain and branched-chain alkyl of up to about 4carbon atoms, and m and n each represent 0, 1 or 2.

[0013] Alternatively, R¹ and R² in combination or collectively mayrepresent a divalent arylene group. The divalent groups which R¹ and R²collectively may represent include radicals having the formula

[0014] wherein

[0015] each of A¹ and A² is an arylene radical, e.g., a divalent,carbocyclic aromatic group containing 6 to 10 ring carbon atoms, whereineach ester oxygen atom of fluorophosphite (I) is bonded to a ring carbonatom of A¹ and A²;

[0016] X is (i) a chemical bond directly between ring carbon atoms of A¹and A² or (ii) an oxygen atom, a group having the formula —(CH₂)_(y)—wherein y is 2 to 4 or a group having the formula

[0017] wherein R⁵ is hydrogen, alkyl or aryl, e.g., the aryl groupsillustrated by formulas (II), (III) and (IV), and R⁶ is hydrogen oralkyl. The total carbon content of the group —C(R⁵)(R⁶)— normally willnot exceed 20 and, preferably, is in the range of 1 to 8 carbon atoms.Normally, when R¹ and R² collectively represent a divalenthydrocarbylene group, the fluorophosphite ester oxygen atoms, i.e. theoxygen atoms depicted in formula (I), are separated by a chain of atomscontaining at least 3 carbon atoms.

[0018] Examples of the arylene groups represented by each of A¹ and A²include the divalent radicals represented by the formulas (V), (VI) and(VII).

[0019] wherein R³ and R⁴ may represent one or more substituentsindependently selected from alkyl, alkoxy, halogen, cycloalkoxy, formyl,alkanoyl, cycloalkyl, aryl, aryloxy, aroyl, carboxyl, carboxylate salts,alkoxycarbonyl, alkanoyloxy, cyano, sulfonic acid, sulfonate salts andthe like. The alkyl moiety of such alkyl, alkoxy, alkanoyl,alkoxycarbonyl and alkanoyloxy groups typically contains up to about 8carbon atoms. Although it is possible for p to represent 0 to 4 and forq to represent 0 to 6, the value of each of p and q usually will notexceed 2. R³ and R⁴ preferably represent a halogen such as chlorine, alower alkyl group, i.e., straight-chain and branched-chain alkyl of upto about 4 carbon atoms, or lower alkoxy; and p and q each represent 0,1 or 2.

[0020] The dihydrocarbyl fluorophosphite compounds that are mostpreferred, e.g., those which exhibit the best stability, are thosewherein the fluorophosphite oxygen atoms are bonded directly to a ringcarbon atom of a carbocyclic, aromatic group, e.g., an aryl or arylenegroup represented by any of formulas (II) through (VII). When R¹ and R²individually each represents an aryl radical, e.g., a phenyl group, itis further preferred that 1 or both of the ring carbon atoms that are ina position ortho to the ring carbon atoms bonded to the fluorophosphiteester oxygen atom are substituted with an alkyl group, especially abranched chain alkyl group such as isopropyl, tert-butyl, tert-octyl andthe like. Similarly, when R¹ and R² collectively represent a radicalhaving the formula

[0021] the ring carbon atoms of arylene radicals A¹ and A² that are in aposition ortho to the ring carbon atoms bonded to the fluorophosphiteester oxygen atom are substituted with an alkyl group, preferably abranched chain alkyl group such as isopropyl, tert-butyl, tert-octyl andthe like.

[0022] The most preferred dihydrocarbyl fluorophosphite compounds havethe general formula:

[0023] wherein R⁷ represents hydrogen, halogen such as chloro or C₁ toC₁₂ alkyl, preferably C₁ to C₄ alkyl; R⁸ represent halogen such aschloro, C₁ to C₁₂ alkyl, preferably C₁ to C₄ alkyl, or C₁ to C₁₂ alkoxy,preferably C₁ to C₄ alkoxy; r is 0, 1 or 2; and X is (i) a chemical bonddirectly between ring carbon atoms of the arylene groups or (ii) a grouphaving the formula

[0024] wherein R⁵ is hydrogen, alkyl or aryl, e.g., the aryl groupsillustrated by formulas (II), (III) and (IV), and R⁶ is hydrogen oralkyl.

[0025] Specific illustrative examples of the phosphite ligandsemployable in the present invention within the scope of generic formulasI-III above include the following phosphite compounds:

[0026] The novel catalyst systems provided by the present inventioncomprise a combination of (a) one or more of the dihydrocarbylfluorophosphite compounds described in detail hereinabove; (b) rhodium;and (c) a Group VIII metal, other than rhodium, or Group VIIImetal-containing compound. The rhodium metal may be provided in the formof various metal compounds such as rhodium carboxylate salts. Rhodiumcompounds that may be used as a source of rhodium for the activecatalyst include rhodium II or rhodium III salts of carboxylic acids,examples of which include di-rhodium tetraacetate dihydrate, rhodium(II)acetate, rhodium(II) isobutyrate, rhodium(II) 2-ethylhexanoate,rhodium(II) benzoate and rhodium(II) octanoate. Also, rhodium carbonylspecies such as Rh₄(CO)₁₂, Rh₆(CO)₁₆ and rhodium(I) acetylacetonatedicarbonyl may be suitable rhodium sources. Additionally, rhodiumorganophosphine complexes such as tris(triphenylphosphine) rhodiumcarbonyl hydride may be used when the phosphine moieties of the complexfed are easily displaced by the fluorophosphite ligands of the presentinvention. Less desirable rhodium sources are rhodium salts of strongmineral acids such as chlorides, bromides, nitrates, sulfates,phosphates and the like. We have found rhodium 2-ethylhexanoate to be aparticularly preferred source of rhodium from which to prepare thecomplex catalyst of the invention because it is a convenient source ofsoluble rhodium, as it can be efficiently prepared from inorganicrhodium salts such as rhodium halides.

[0027] The ratio of gram moles dihydrocarbyl fluorophosphite ligand togram atoms rhodium normally is at least 1:1 and can vary over a widerange, e.g., gram mole fluorophosphite:gram atom transition metal ratiosof about 1:1 to 500:1. The gram mole fluorophosphite:gram atom rhodiumratio preferably is in the range of about 5:1 up to 150:1 with ratios inthe range of about 5:1 to 100:1 being particularly preferred.

[0028] The amount of the stabilizer Group VIII metal, i.e., the GroupVIII metal other than rhodium (“other Group VIII metal”), present in thenovel catalyst systems provided by the present invention typicallyshould provide up to a 10-fold gram atom excess of the other Group VIIImetal based on the gram atoms of rhodium present in the catalyst system.Preferably, the gram atom ratio of the other Group VIII metal:rhodiummetal is in the range of about 1:1 to 5:1. In the practice of thepresent invention, the other Group VIII metal may be introduced to thecatalyst precursor materials or directly into the hydroformylationreactor in the form of stable precursor compounds. Examples of stableprecursor compounds are the carbonyls, carboxylates, oxides,acetonylacetonates and phosphates of the other Group VIII metals. Thepreferred Group VIII metals for use as stabilizers are platinum, cobalt,ruthenium and palladium. Normally, the precursor of the other Group VIIImetal will not contain any known catalyst poisons such as sulfur orinorganic halides. The metal stabilizer precursor compounds may be addedto the hydroformylation reaction mixture as a single batch as acomponent of the overall catalyst or in small quantities over anextended period of time. Furthermore, if the concentration of the otherGroup VIII metal stabilizer should decrease over time, additional GroupVIII metal stabilizer may be added during the hydroformylation processto maintain the stabilizer at an effective level in the process.

[0029] A second embodiment of our invention concerns a novel catalystsolution comprising (a) one or more of the fluorophosphite ligands offormula (I), (b) rhodium, (c) a Group VIII metal, other than rhodium, orGroup VIII metal-containing compound and (d) a hydroformylation solvent.This embodiment comprises a solution of the active catalyst in which acarbonylation process such as the hydroformylation of anethylenically-unsaturated compound may be carried out.

[0030] The hydroformylation reaction solvent may be selected from a widevariety of compounds, mixture of compounds, or materials that are liquidat the pressure at which the process is being operated, do not affectadversely the hydroformylation process, and are inert with respect tothe catalyst, olefin, hydrogen and carbon monoxide. Such compounds andmaterials include various alkanes, cycloalkanes, alkenes, cycloalkenes,carbocyclic aromatic compounds, alcohols, esters, ketones, acetals,ethers and water. Specific examples of such solvents include alkane andcycloalkanes such as dodecane, decalin, octane, iso-octane mixtures,cyclohexane, cyclo-octane, cyclododecane, methylcyclohexane; aromatichydrocarbons such as benzene, toluene, xylene isomers, tetralin, cumene,alkyl-substituted aromatic compounds such as the isomers ofdiisopropylbenzene, triisopropylbenzene and tert-butylbenzene; alkenesand cycloalkenes such as 1,7-octadiene, dicyclopentadiene,1,5-cyclooctadiene, octene-1, octene-2,4-vinylcyclohexene, cyclohexene,1,5,9-cyclododecatriene, 1-pentene; crude hydrocarbon mixtures such asnaphtha, mineral oils and kerosene; high-boiling esters such as2,2,4-trimethyl-1,3-pentanediol mono- and di-isobutyrate and dioctylphthalate; hydrogenated polydecenes, e.g., materials marketed under thetradenames Durasyn170 and Durasyn 180; and epoxidized soybean oil. Thealdehyde product of the hydroformylation process also may be used. Inpractice, the preferred solvent is the higher boiling by-products thatare naturally formed during the process of the hydroformylation reactionand the subsequent steps, e.g., distillations, that are required foraldehyde product isolation. The main criteria for the solvent is that itdissolves the catalyst and olefin substrate and does not act as a poisonto the catalyst. Preferred solvents for the production of volatilealdehydes, e.g., propionaldehyde and the butyraldehydes, are those thatare sufficiently high boiling to remain, for the most part, in a gassparged reactor. Solvents and solvent combinations that are preferredfor use in the production of less volatile and non-volatile aldehydeproducts include 1-methyl-2-pyrrolidinone, dimethylformamide,perfluorinated solvents such as perfluorokerosene, sulfolane, water, andhigh boiling hydrocarbon liquids as well as combinations of thesesolvents. We have found that non-hydroxylic compounds, in general, andhydrocarbons, in particular, may be used advantageously as thehydroformylation solvent since their use can minimize decomposition ofthe fluorophosphite ester ligands.

[0031] The concentration of the rhodium, ligand and other Group VIIImetal in the hydroformylation solvent or reaction mixture is notcritical for the successful operation of our invention. As mentionedhereinabove, a gram mole ligand:gram atom rhodium ratio of at least 1:1normally is maintained in the reaction mixture and the gram atom ratioof the other Group VIII metal:rhodium metal preferably is in the rangeof about 1:1 to 5:1. The absolute concentration of rhodium in thereaction mixture or solution may vary from 1 mg/liter up to 5000mg/liter or more. When the process is operated within the practicalconditions of this invention, the concentration of rhodium in thereaction solution normally is in the range of about 20 to 300 mg/liter.Concentrations of rhodium lower than this range generally do not yieldacceptable reaction rates with most olefin reactants and/or requirereactor operating temperatures that are so high as to be detrimental tocatalyst stability. Higher rhodium concentrations are not preferredbecause of the high cost of rhodium. The concentration of thedihydrocarbyl fluorophosphite ligand in the hydroformylation solvent orreaction mixture typically is between about 0.005 and 15 weight percentbased on the total weight of the reaction mixture. More typically, theligand concentration is between 0.001 and 10 weight percent, andpreferably is between about 0.05 and 5 weight percent on that basis.

[0032] No special or unusual techniques are required for preparing thecatalyst systems and solutions of the present invention, although it ispreferred, to obtain a catalyst of high activity, that all manipulationsof the rhodium and fluorophosphite ligand components be carried outunder an inert atmosphere, e.g., nitrogen, argon and the like. Thedesired quantities of a suitable rhodium compound, ligand and an otherGroup VIII compound are charged to the reactor in a suitable solvent.The sequence in which the various catalyst components or reactants arecharged to the reactor is not critical.

[0033] The reaction mixtures used in the process of the presentinvention are comprised of (a) one or more of the dihydrocarbylfluorophosphite compounds described in detail hereinabove; (b) rhodium;and (c) a Group VIII metal, other than rhodium, or Group VIIImetal-containing compound. The rhodium functions as a hydroformylationcatalyst in the form of a complex catalyst which is formed in situ fromthe rhodium, carbon monoxide, the dihydrocarbyl fluorophosphite ligandand hydrogen. Additional components, such as the olefin, may also bebonded to the rhodium at various points in the catalytic cycle. Therhodium catalyst and catalytic precursor compounds are preferably freeof any poisons such as sulfur compounds, inorganic chlorides andbromides or readily hydrolyzable organic halogen compounds. Thereactants and catalyst components should also be free of any materialsthat will promote by-product formation from the product aldehyde.Materials known to promote by-product formation from the productaldehyde include iron compounds, strong acids or bases, and amines.

[0034] The third embodiment of the present invention pertains to ahydroformylation process utilizing the above-described catalyst systemsand solutions. The process of the present invention therefore is aprocess for preparing an aldehyde which comprises contacting an olefin,hydrogen and carbon monoxide with a solution of a catalyst systemcomprising (1) one or more of the above-described dihydrocarbylfluorophosphite compounds; (2) rhodium; and (3) a Group VIII metal,other than rhodium, or Group VIII metal-containing compound, wherein theratio of gram moles ligand:gram atom rhodium is at least 1:1. Theolefins that may be hydroformylated by means of our novel processcomprise aliphatic, including ethylenically-unsaturated, low molecularweight polymers, alicyclic, aromatic and heterocyclic mono-, di- andtri-olefins containing up to about 40 carbon atoms. Examples of thealiphatic olefins that may be utilized in the process include straight-and branched-chain, unsubstituted and substituted, aliphaticmono-α-olefins containing up to about 20 carbon atoms. Examples of thegroups that may be present on the substituted mono-α-olefins includehydroxy; alkoxy including ethers and acetals; alkanoyloxy such asacetoxy; amino including substituted amino; carboxy; alkoxycarbonyl;carboxamido; keto; cyano; and the like. Preferred aliphaticmono-α-olefins have the general formulas:

[0035] wherein

[0036] R⁹ is hydrogen or straight- or branched-chain alkyl of up toabout 8 carbon atoms;

[0037] R¹⁰ is straight- or branched-chain alkylene of up to about 18carbon atoms; and

[0038] R¹¹ is hydroxy, alkoxy of up to about 4 carbon atoms, alkanoyloxyof up to about 4 carbon atoms, carboxyl or alkoxycarbonyl of 2 to about10 carbon atoms.

[0039] Specific examples of the aliphatic mono-α-olefins includeethylene, propylene, 1-butene, 1-octene, allyl alcohol and3-acetoxy-1-propene.

[0040] The aliphatic, di-olefins may contain up to about 40 carbonatoms. Preferred aliphatic, di-olefins have the general formula:

[0041] wherein R¹² is straight- or branched-chain alkylene having 1 toabout 18 carbon atoms.

[0042] The cyclic olefins which may be used in the hydroformylationprocess of the present invention may be cycloalkenes, e.g., cyclohexene,1,5-cyclooctadiene, and cyclodecatriene, and from variousvinyl-substituted cycloalkanes, cycloalkenes, heterocyclic and aromaticcompounds. Examples of such cyclic olefins include 4-vinylcyclohexene,1,3-cyclo-hexadiene, 4-cyclohexene-carboxylic acid, methyl4-cyclohexene-carboxylic acid, 1,4-cyclooctadiene and1,5,9-cyclododecatriene.

[0043] Mixtures of olefins also can be used in the practice of thisinvention. The mixtures may be of the same carbon number such asmixtures of n-octenes or it may represent refinery distillation cutswhich will contain a mixture of olefins over a range of several carbonnumbers.

[0044] The olefin reactants which are particularly preferred comprisemono-α-olefins of 2 to 10 carbon atoms, especially propylene.

[0045] The reaction conditions used are not critical for the operationof the process and conventional hydroformylation conditions normally areused. The process requires that an olefin is contacted with hydrogen andcarbon monoxide in the presence of the novel catalyst system describedhereinabove. While the process may be carried out at temperatures in therange of about 20 to 200° C., the preferred hydroformylation reactiontemperatures are from about 50 to 150° C. with the most favored reactiontemperatures ranging from about 80 to 130° C. Higher reactortemperatures are not favored because of increased rates of catalystdecomposition while lower reactor temperatures result in relatively slowreaction rates.

[0046] The hydroformylation process of the present invention normally iscarried out at elevated pressures in the range of about 0.7 to 69 barsgauge (barg; about 10 to 1000 pounds per square inch—psig), preferablyin the range of about 6.9 to 27.6 barg (about 100 to 400 psig). Lowerpressures result in the rate of reaction being economically unattractivewhereas higher pressures, e.g., greater than 69 barg, result inincreased gas compression and equipment costs. In the present invention,the synthesis gas, i.e., CO and H₂, is introduced into the reactor in acontinuous manner by means, for example, of a compressor. The partialpressures of the ratio of the hydrogen to carbon monoxide in the feed isselected according to the desired linear to branched isomer ratio in theproduct. Generally, the partial pressure of hydrogen and carbon monoxidein the reactor is maintained within the range of about 0.4 to 13 barg(about 5 to 188 psig) for each gas. The partial pressure of carbonmonoxide in the reactor is maintained within the range of about 0.4 to13 barg (about 5 to 188 psig) and is varied independently of thehydrogen partial pressure.

[0047] The molar ratio of hydrogen to carbon monoxide can be variedwidely within these partial pressure ranges for the hydrogen and carbonmonoxide. The ratios of the hydrogen to carbon monoxide and the partialpressure of each in the synthesis gas can be readily changed by theaddition of either hydrogen or carbon monoxide to the synthesis gasstream. We have found that with the dihydrocarbyl fluorophosphiteligands present in the catalyst of the present invention, the ratio oflinear to branched products can be varied widely by changing the partialpressures of the carbon monoxide in the reactor. For example, thehydrogen:carbon monoxide mole ratio in the reactor may vary from about10:1 to 1:10.

[0048] The amount of olefin present in the reaction mixture also is notcritical. For example, relatively high-boiling olefins such as 1-octenemay function both as the olefin reactant and the process solvent. In thehydroformylation of a gaseous olefin feedstock such as propylene, thepartial pressures in the vapor space in the reactor typically are in therange of about 0.01 to 34 barg. In practice the rate of reaction isfavored by high concentrations of olefin in the reactor. In thehydroformylation of propylene, the partial pressure of propylenepreferably is greater than 0.4 barg, e.g., from about 0.4 to 9 barg. Inthe case of ethylene hydroformylation, the preferred partial pressure ofethylene in the reactor is greater than 0.01 barg.

[0049] Any of the known hydroformylation reactor designs orconfigurations may be used in carrying out the process provided by thepresent invention. Thus, a gas-sparged, vapor take-off reactor design asdisclosed in the examples set forth herein may be used. In this mode ofoperation the catalyst which is dissolved in a high boiling organicsolvent under pressure does not leave the reaction zone with thealdehyde product which is taken overhead by the unreacted gases. Theoverhead gases then are chilled in a vapor/liquid separator to liquifythe aldehyde product and the gases can be recycled to the reactor. Theliquid product is let down to atmospheric pressure for separation andpurification by conventional technique. The process also may bepracticed in a batchwise manner by contacting the olefin, hydrogen andcarbon monoxide with the present catalyst in an autoclave.

[0050] A reactor design where catalyst and feedstock are pumped into areactor and allowed to overflow with product aldehyde, i.e. liquidoverflow reactor design, is also suitable. For example, high boilingaldehyde products such as nonyl aldehydes may be prepared in acontinuous manner with the aldehyde product being removed from thereactor zone as a liquid in combination with the catalyst. The aldehydeproduct may be separated from the catalyst by conventional means such asby distillation or extraction and the catalyst then recycled back to thereactor. Water soluble aldehyde products, such as hydroxy butyraldehydeproducts obtained by the hydroformylation of allyl alcohol, can beseparated from the catalyst by extraction techniques. A trickle-bedreactor design also is suitable for this process. It will be apparent tothose skilled in the art that other reactor schemes may be used withthis invention.

[0051] The other Group VIII metal present in the catalyst compositionsof the present invention reduces the generation of the hydrogen fluorideby increasing the stability of the catalyst components. When thecatalyst is stabilized against degradation, less hydrogen fluoride isgenerated and less hydrogen fluoride is found in the reaction product.The stabilization factor is best illustrated in data from a continuoushydroformylation bench unit used to prepare butyraldehydes. For example,in the absence of an other Group VIII metal, the hourly products of thebench unit runs will contain about 0.10 milligrams of hydrogen fluorideper 100 grams of butyraldehyde. The addition of the other Group VIIImetal reduces the amount of hydrogen fluoride measured in the aldehyde,often as much as thirty percent or more as shown by the examples setforth below. Thus, a further embodiment of our invention provides amethod for reducing the amount of HF formed in a hydroformylationreaction utilizing rhodium-fluorophosphite catalyst complexes ascatalyst, which comprises charging the reaction vessel with anHF-reducing effective amount of an other Group VIII compound.

EXAMPLES

[0052] The various embodiments of the present invention are furtherillustrated by the following examples. The hydroformylation process inwhich propylene is hydroformylated to produce butyraldehydes is carriedout in a vapor take-off reactor consisting of a vertically arrangedstainless steel pipe having a 2.5 cm inside diameter and a length of 1.2meters. The reactor is encased in an external jacket that is connectedto a hot oil machine. The reactor has a filter element welded into theside down near the bottom of the reactor for the inlet of gaseousreactants. The reactor contains a thermowell which is arranged axiallywith the reactor in its center for accurate measurement of thetemperature of the hydroformylation reaction mixture. The bottom of thereactor has a high pressure tubing connection that is connected to across. One of the connections to the cross permits the addition ofnon-gaseous reactants such as octene-1 or make-up solvent, another leadsto the high-pressure connection of a differential pressure (D/P) cellthat is used to measure catalyst level in the reactor and the bottomconnection is used for draining the catalyst solution at the end of therun.

[0053] In the hydroformylation of propylene in a vapor take-off mode ofoperation, the hydroformylation reaction mixture or solution containingthe catalyst is sparged under pressure with the incoming reactants ofpropylene, hydrogen and carbon monoxide as well as any inert feed suchas nitrogen. As butyraldehyde is formed in the catalyst solution, it andunreacted reactant gases are removed as a vapor from the top of thereactor by a side-port. The vapor removed is chilled in a high-pressureseparator where the butyraldehyde product is condensed along with someof the unreacted propylene. The uncondensed gases are let down toatmospheric pressure via the pressure control valve. These gases passthrough a series of dry-ice traps where any other aldehyde product iscollected. The product from the high-pressure separator is combined withthat of the traps, and is subsequently weighed and analyzed by standardgas/liquid phase chromatography (GLC) techniques for the net weight andnormal/iso ratio of the butyraldehyde product.

[0054] The gaseous feeds to the reactor are fed to the reactor via twincylinder manifolds and high-pressure regulators. The hydrogen passesthrough a mass flow controller and then through a commercially available“Deoxo” (registered trademark of Engelhard Inc.) catalyst bed to removeany oxygen contamination. The carbon monoxide passes through an ironcarbonyl removal bed (as disclosed in U.S. Pat. No. 4,608,239), asimilar “Deoxo” bed heated to 125° C., and then a mass flow contoller.Nitrogen can be added to the feed mixture as an inert gas. Nitrogen,when added, is metered in and then mixed with the hydrogen feed prior tothe hydrogen Deoxo bed. Propylene is fed to the reactor from feed tanksthat are pressurized with hydrogen and is controlled using a liquid massflow meter. All gases and propylene are passed through a preheater toinsure complete vaporization of the liquid propylene prior to enteringthe reactor.

[0055] Fluoride measurements were made with a fluoride ion selectiveelectrode (Orion Research Inc. product 9609BN) in combination with aMetrohm 751 GPD Titrino unit. All measurements, separations anddilutions were carried out in plastic laboratory equipment. All samplesanalyzed for fluoride content were collected and held in plasticcontainers. A measured portion of the product aldehyde (20 ml) wasextracted with an equal volume (20 ml) of a constant ion strength buffersuch as TISAB II (Total Ion Strength Adjustment Buffer) with 1,2cyclohexane diamine tetraacetic acid—CDTA (a product of Orion Research,Inc.), the aqueous extract diluted with an equal volume of deionizedwater (20 ml), and the conductivity of the solution was measured andcompared to a previously prepared calibration curve.

Comparative Example 1

[0056] A comparison bench unit experiment without an added other GroupVIII metal was conducted by preparing a catalyst composed of 4.25 gramsof a dihydrocarbyl fluorophosphites having the formula:

[0057] (t-Bu=tertiary butyl, Me=methyl) with 7.5 milligrams of rhodium(as rhodium 2-ethylhexanoate) in 190 milliliters of dioctylphthalate.The mixture was stirred and heated under nitrogen until a homogenousmixture was obtained. The mixture was charged to the reactor describedpreviously and the reactor sealed. The reactor pressure control was setat 17.9 barg (260 psig) and the external oil jacket on the reactor washeated to 105° C. Hydrogen, carbon monoxide, nitrogen and propylenevapors were fed through the frit at the base of the reactor and thereactor allowed to build pressure. The hydrogen and carbon monoxide werefed to the reactor at a rate of 3.35 standard liters per minute. Thenitrogen feed was set at 1.0 standard liter per minute. The propylenewas metered as a liquid and fed at a rate of 212 grams per hour. Thetemperature of the external oil was modified to maintain an internalreactor temperature of 115° C. The unit was operated for 5 hours andhourly samples taken. The hourly samples were analyzed as describedabove and the fluoride content determined. The fluoride content wasfound to consistently be about 0.105 milligrams of hydrogen fluoride per100 grams of butyraldehyde.

Example 1-7

[0058] The experimental procedure of Example 1 was repeated except thatanother Group VIII was added to the catalyst mixture. The results ofthese experiments are tabulated in the Table below which specified theGroup VIII metal compound and the amount thereof used in each ofExamples 1-7 and wherein Acac is acetylacetonate and Hydrogen FluorideContent refers to the milligram HF per 100 grams of butyraldehydesproduced. The results clearly show that the presence of the additionalGroup VIII metal compound to the catalyst reduces the amount of hydrogenfluoride in the product aldehyde. TABLE Group VIII Example Metal AmountHydrogen Fluoride Number Compound Added Content 2 Ru(Acac)₃ 0.03 g 0.0463 Ru(Acac)₃ 0.15 g 0.047 4 Co(Acac)₃ 0.02 g 0.033 5 Pd(acetate)₂ 0.02 g0.056 6 Co(Acac)₃ 0.10 g 0.035 7 Pt(Acac)₃ 0.03 g 0.018 8 Ru₃(CO)₁₂ 0.05g 0.045

[0059] The invention has been described in detail with particularreference to preferred embodiments thereof, but it will be understoodthat variations and modifications will be effected within the spirit andscope of the invention.

1-11. (canceled)
 12. A process for preparing an aldehyde which comprisescontacting an olefin, hydrogen and carbon monoxide with a solution of acatalyst system comprising (1) one or more dihydrocarbyl fluorophosphiteligands having the formula

wherein R¹ and R² are aromatic hydrocarbyl radicals which contain atotal of up to 40 carbon atoms; (2) rhodium, wherein the ratio of grammoles fluorophosphite ligand to gram atoms rhodium is at least 1:1; (3)a Group VIII metal or Group VIII metal-containing compound-, in anamount effective to reduce the formation of HF during the process,wherein the Group VIII metal or Group VIII metal-containing compounddoes not contain rhodium; and (4) a hydroformylation solvent. 13.Process according to claim 12 wherein the concentration of rhodium inthe solution is in the range of about 30 to 300 mg per liter; theprocess is carried out at a temperature of about 50 to 135° C. and apressure in the range of 0.7 to 69 bars gauge; and the Group VIII metalis platinum, cobalt, ruthenium or palladium.
 14. Process according toclaim 12 wherein the concentration of rhodium in the solution is in therange of about 50 to 300 mg per liter; the process is carried out at atemperature of about 50 to 135° C. and a at a pressure in the range of0.7 to 69 bars gauge; R¹ and R² aryl groups independently selected fromthe group consisting of:

wherein R³ and R⁴ are independently selected from the group consistingof alkyl, alkoxy, halogen, cycloalkoxy, formyl, alkanoyl, cycloalkyl,aryl, aryloxy, aroyl, carboxyl, carboxylate salts, alkoxycarbonyl,alkanoyloxy, cyano, sulfonic acid and sulfonate salts in which the alkylmoiety of said alkyl, alkoxy, alkanoyl, alkoxycarbonyl and alkanoyloxygroups contains up to 8 carbon atoms; m and n each is 0, 1 or 2; and theratio of gram moles dihydrocarbyl fluorophosphite ligand to gram atomsrhodium is about 1:1 to 500:1; and the Group VIII metal is selected fromthe group consisting of platinum, cobalt, ruthenium, and palladium,wherein the gram atom ratio of the Group VIII metal:rhodium metal is inthe range of about 1:1 to 5:1.
 15. Process according to claim 12 whereinthe olefin is a mono-α-olefin of 2 to 10 carbon atoms.
 16. Processaccording to claim 14 wherein the olefin is a mono-α-olefin of 2 to 10carbon atoms.
 17. Process according to claim 12 wherein theconcentration of rhodium in the solution is in the range of about 30 to300 mg per liter; the process is carried out at a temperature of about50 to 135° C. and a at a pressure in the range of 0.7 to 69 bars gauge;R¹ and R² collectively represent a divalent aromatic hydro-carbylenegroup containing 12 to 36 carbon atoms; and the Group VIII metal isselected from the group consisting of platinum, cobalt, ruthenium, andpalladium.
 18. Process according to claim 17 wherein the ratio of grammoles dihydrocarbyl fluorophosphite ligand to gram atoms rhodium isabout 1:1 to 500:1 and R¹ and R² collectively represent an arylene grouphaving the formula

or a radical having the formula

wherein each of A¹ and A² is an arylene radical having formula (V), (VI)or (VII) above wherein each ester oxygen atom of fluorophosphite (I) isbonded to a ring carbon atom of A¹ and A²; X is (i) a chemical bonddirectly between ring carbon atoms of A¹ and A²; or (ii) an oxygen atom,a group having the formula —(CH₂)_(y)— wherein y is 2 to 4, or a grouphaving the formula

wherein R⁵ is hydrogen, alkyl or aryl; R⁶ is hydrogen or alkyl; and thegroup —C(R⁵)(R⁶)— contains up to 8 carbon atoms; and wherein R³ and R⁴are independently selected from the group consisting of alkyl, alkoxy,halogen, cycloalkoxy, formyl, alkanoyl, cycloalkyl, aryl, aryloxy,aroyl, carboxyl, carboxylate salts, alkoxycarbonyl, alkanoyloxy, cyano,sulfonic acid, and sulfonate salts in which the alkyl moiety of saidalkyl, alkoxy, alkanoyl, alkoxycarbonyl and alkanoyloxy groups containsup to 8 carbon atoms; p and q each is 0, 1 or
 2. 19. Process accordingto claim 18 wherein the dihydrocarbyl fluorophosphite ligand has theformula

wherein R⁷ represents hydrogen, halogen or C₁ to C₁₂ alkyl; R⁸represents halogen, C₁ to C₁₂ alkyl or C₁ to C₁₂ alkoxy; r is 0, 1 or 2;and X is a group having the formula

wherein R⁵ is hydrogen, alkyl or aryl; and R⁶ is hydrogen or alkyl. 20.A process for preparing an aldehyde which comprises contacting anolefin, hydrogen and carbon monoxide with a solution of a catalystsystem comprising (1) a dihydrocarbyl fluorophosphite ligand of theformula

wherein R⁷ represents hydrogen, chloro or C₁ to C₄ alkyl; R⁸ representschloro, C₁ to C₄ alkyl or C₁ to C₄ alkoxy; r is 0, 1 or 2; and X is agroup having the formula

wherein R⁵ is hydrogen, alkyl or aryl; and R⁶ is hydrogen or alkyl; (2)rhodium, wherein the ratio of gram moles dihydrocarbyl fluorophosphiteligand to gram atoms rhodium is about 1:1 to 500:1; and (3) a Group VIIImetal selected from the group consisting of platinum, cobalt, ruthenium,and palladium wherein the gram atom ratio of the Group VIIImetal:rhodium metal is in the range of about 1:1 to 5:1; wherein theolefin is a mono-α-olefin of 3 to 8 carbon atoms; and the process iscarried out at a temperature of 50 to 135° and the normal to iso ratioof the aldehyde product is controlled by varying the partial pressure ofcarbon monoxide in the reactor gas between 0.4 and 13 barg.
 21. Processaccording to claim 20 wherein the concentration of rhodium in thesolution is in the range of about 30 to 300 mg per liter; thefluorophosphite ligand has the formula

wherein t-Bu is tertiary butyl and Me is methyl; the ratio of gram molesfluorophosphite ligand to gram atoms rhodium is about 5:1 to 150:1; theolefin is a mono-α-olefin of 2 to 10 carbon atoms; and the process iscarried out at a temperature of about 50 to 135° C. at a pressure in therange of 0.7 to 69 bars gauge.